//
// Created by Administrator on 2025/9/4.
//

#include <iostream>
#include <set>

int main()
{
    std::set<int> iset = {0,1,2,3,4,5,6,7,8,9};
    std::set<int>::iterator set_it = iset.begin();
    if (set_it != iset.end()) {
        // *set_it = 42; // error: keys in a set are read-only
        std::cout << *set_it << std::endl; // ok: can read the key
    }
}
